The purpose of this project is to develop a safe, relatively inexpensive, accurate and non-invasive technique for the prenatal diagnosis of genetic disorders by isolating fetal cells in maternal peripheral blood during the first trimester of pregnancy. Cyto- trophoblast-specific antibodies will be produced and will be used to isolate the fetal cells with the aid of a fluorescence-activated cell sorter. The isolated fetal cells can then be used for the prenatal diagnosis of cytogenetic, biochemical or DNA abnormalities.